Preparation of organic/inorganic composites by deposition of silica onto shell layers of polystyrene (core)/poly[2-(N,N-dimethylamino)ethyl methacrylate] (shell) particles.

Organic/inorganic composites were prepared by catalytic hydrolysis and subsequent condensation of tetraethoxysilane (TEOS) in a shell layer of core-shell polymer particles. First, core-shell particles were prepared by emulsifier-free emulsion polymerization of styrene (St) with 2-chloropropionyloxyethyl methacrylate (CPEM) using potassium persulfate as an initiator, followed by surface-initiated activator generated electron transfer-atom transfer radical polymerization (AGET-ATRP) of 2-(N,N-dimethylamino)ethyl methacrylate (DMAEMA). Dynamic light scattering revealed that hydrodynamic diameter of the particle increased from 482 to 931 nm after AGET-ATRP of DMAEMA. The amount of grafted DMAEMA was determined to be ca. 10 mol% with respect to (wrt) St by (1)H NMR. Second, the composite particles were prepared by adding TEOS into a water/methanol dispersion of the P(St-CPEM)-g-P(DMAEMA). The P(St-CPEM)-g-P(DMAEMA)-SiO(2) composite particles containing ca. 50 wt.% of silica wrt the total weight were obtained. Hollow silica shell particles were also obtained by extraction of polymer components from the composites with tetrahydrofuran.